Many medical procedures require the delineation of certain objects shown in medical images. Examples are the organ-of-risk and target volume delineation in computed tomography (CT) images for radiotherapy planning or tumor delineation in CT, magnetic resonance (MR) or functional images for diagnosis. Medical image segmentation applications require manual delineation of the ‘object to segment’ for training and evaluation of automatic procedures.
Such manual delineation tasks require tools to mark the object or the surface of the object when shown on a screen. Automatic 3D delineation procedures require efficient viewing devices for quality assurance of the results and also delineation tools, if possible 3D tools, for manual correction, where necessary.
Most medical image data are three dimensional (3D) volumes or even higher dimensional, e.g. video sequences or if images acquired from several types of imaging equipment are to be considered simultaneously. Only two dimensional (2D) data can be displayed fully on screen and a 3D delineation interaction is displayed on a 2D sub-volume (“slice”) of the 3D volume. The restricted 2D view on 3D image data makes handling of the 3D delineation tool at times cumbersome.